Lawrence A. Rowe

The design of POSTGRES

This paper presents the preliminary design of a new database management system, called POSTGRES, that is the successor to the INGRES relational database system. The main design goals of the new system are toprovide better support for complex objects, provide user extendibility for data types, operators and access methods, provide facilities for active databases (i.e., alerters and triggers) and inferencing including forward- and backward-chaining, simplify the DBMS code for crash recovery, produce a design that can take advantage of optical disks, workstations composed of multiple tightly-coupled processors, and custom designed VLSI chips, and make as few changes as possible (preferably none) to the relational model. The paper describes the query language, programming language interface, system architecture, query processing strategy, and storage system for the new system.

Comparison of video shot boundary detection techniques

Many algorithms have been proposed for detecting video shot boundaries and classifying shot and shot transition types. Few published studies compare available algorithms, and those that do have looked at limited range of test material. This paper presents a comparison of several shot boundary detection and classification techniques and their variations including histograms, discrete cosine transform, motion vector, and block matching methods. The performance and ease of selecting good thresholds for these algorithms are evaluated based on a wide variety of video sequences with a good mix of transition types. Threshold selection requires a trade-off between recall and precision that must be guided by the target application.

The implementation of POSTGRES

The design and implementation decisions made for the three-dimensional data manager POSTGRES are discussed. Attention is restricted to the DBMS backend functions. The POSTGRES data model and query language, the rules system, the storage system, the POSTGRES implementation and the current status and performance are discussed. >

A Continuous Media Player

The design and implementation of a continuous media player for Unix workstations is described. The player can play synchronized digital video and audio read from a file server. The system architecture and results of preliminary performance experiments are presented.

Composable ad-hoc mobile services for universal interaction

This paper introduces the notion of “universal interaction,” allowing a device to adapt its functionality to exploit services it discovers as it moves into a new environment. Users wish to invoke services - such as controlling the lights, printing locally, or reconfiguring the location of DNS servers from their mobile devices. But aptiotistandardizationof interfaces and methods for service invocation is infeasible. Thus, the challenge is to develop a new service architecture that supports heterogeneity in client devices and controlled objects, and which makes minimal assumptions about standard interfaces and control protocols. There are five components to a comprehensive solution to this problem: 1) allowing device mobility, 2) augmenting controllable objects to make them network-accessible, 3) building an underlying discovery architecture, 4) mapping between exported object interfaces and client device controls, and 5) building complex behaviors from underlying composableobjects. We motivate the need for these components by using an example scenario to derive the design requirements for our mobile services architecture. We then present a prototype implementation of elements of the architecture and some example services using it, including controls to audio/visual equipment, extensible mapping, server autoconfiguration, location tracking, and local printer access.

Visual similarity of pen gestures

Pen-based user interfaces are becoming ever more popular. Gestures (i.e., marks made with a pen to invoke a command) are a valuable aspect of pen-based UIs, but they also have drawbacks. The challenge in designing good gestures is to make them easy for people to learn and remember. With the goal of better gesture design, we performed a pair of experiments to determine why users find gestures similar. From these experiments, we have derived a computational model for predicting perceived gesture similarity that correlates 0.56 with observation. We will incorporate the results of these experiments into a gesture design tool, which will aid the pen-based UI designer in creating gesture sets that are easier to learn and more memorable.

Data abstraction, views and updates in RIGEL

Language constructs to support the development of data base applications provided in the programming language rigel are described. First, the language type system includes relations, views, and tuples as built-in types. Tuple-values are introduced to provide more flexibility in writing procedures that update relations and views.Second, an expression that produces sequences of values, called a generator, is defined which integrates relational query expressions with other iteration constructs found in general-purpose programming languages. As a result, relational expressions can be used in new contexts (e.g., as parameters to procedures) to provide new capabilities (e.g., programmer-defined aggregate functions).Lastly, a data abstraction facility, unlike those proposed for other data base programming languages, is described. It provides a better notation to specify the interface between a program and a data base and to support the disciplined use of views.All of these constructs are integrated into a sophisticated programming environment to enhance the development of well-structured programs.

Third-generation database system manifesto

The preparation of beehives from a synthetic resinous material which is acceptable to the bees, which is not attacked by vermin, and which exhibits the requisite physical properties to provide a desirable beehive is accomplished by assembling the hives from molded urethane foam panels, the urethane foam being formulated so as to produce a product which is not rejected by the bees and which does not make the bees nervous or otherwise interfere with their normal habits in secreting honey in said beehive.

Cache consistency and concurrency control in a client/server DBMS architecture

This, paper. examines five application cache consistency algorithms m a cltent/server database system: two-phase locking, certification, callback locking, no-wait locking, and no-wait locking with notification. A simulator was developed to compare the average transaction respnse time and server throughput for these algorithms under different workloads and system configurations. Two-phase locking and callback locking dominate no-wait locking and no-wait locking with notification when the server or the network is a bottleneck. Callback locking is better than two-phase locking when the inter-transaction locality is high or when intertrensaction locality is medium and the probability of object update is low. When there is no network delay and the server is very fast, no-wait locking with notification end callback locking dominate two-phase and no-wait locking.

Implications for a gesture design tool

Interest in pen-based user interfaces is growing rapidly. Onepotentially useful feature of pen-based user interfaces isgestures, that is, a mark or stroke that causes a command toexecute. Unfortunately, it is difficult to design gestures that areeasy 1) for computers to recognize and 2) for humans to learn andremember. To investigate these problems, we built a prototype tooltypical fo those used for designing gesture sets. An experiment wasthen performed to gain insight into the gesture design process andto evaluate this style of tool. The experiment confirmed thatgesture design is very difficult and suggested several ways inwhich current tools can be improved. The most important improvementis to make the tools more active and provide more guidance fordesigners. This paper describes the gesture design tool, theexperiment, and its results.